A relay is a disconnecting or breaking and connecting or closing device that can frequently disconnect or break, carry and connect or close a normal current and a regulated overload current. An existing relay is an electric device that closes the contacts by means of a magnetic field created by a current flowing through a coil, so as to control the load. It is widely used in the fields o electric power, electric distribution, electric consumption, and so on.
In some alternating current or direct current contactors (relays), a framework main body, a lead terminal portion, a movable spring portion, a magnetic circuit system, and pushing mechanism are generally included. The lead terminal portion includes a lead terminal and a stationary contact; the stationary contact is fixed to the bottom of the lead terminal. The movable contact is fixed to the movable spring piece of the movable spring portion and the movable spring portion is correspondingly located inside the framework main body and is pushed by it pushing mechanism. The stationary contact of the lead terminal portion is matched with the movable contact of the movable spring portion, respectively, so as to achieve closing or breaking of the relay. Here, the main material of the framework main body is plastic.
However, when the relay is applied for a relatively higher load, i.e., a circuit having a disconnecting or breaking voltage higher than 10V and a current over 100 mA, a conductive gas mass, which is called electric arc, with extremely high temperature and brightness is created m the contact gap (or to say, arc gap). Electric arcs are a type or aerial discharge. In case that the electric arc strikes the plastic material around the contact, the plastic may be carbonized, the insulation property to be decreased sharply, and the relay may be even burned in a serious situation.
In the prior direct current relays, another solution is that the whole framework is made of a ceramic material, such as the relays in the disclosure of Chinese patent publication CN 102737914A. However, due to the properties of ceramic materials, such framework is typically complex in structure, uncertain in size, and large in weight, and thusly resulting a high cost.
Such prior relay generally comprises pushing mechanism and a framework portion, the pushing mechanism comprising a movable spring portions, a pushing rod portion, compression spring, a stationary iron core, a movable iron core and a return force spring, wherein the return force spring is mounted between the movable iron core and the stationary iron core. In that case, countersinks are required to be provided in the movable iron core and the stationary iron core, and thusly allowing the both ends of the return for spring to be positioned into the countersinks in the movable and stationary iron cores, respectively. Due to such structure, the opposing magnetic pole area between the movable iron core and the stationary iron core will be decreased, and thusly decreasing the driving force and holding three of the iron cores. In order to keep the driving force and holding force of the iron cores, a larger coil is usually required, resulting an increased cost and increased size of the product. The framework portion typically comprises a lead terminal portion and a framework acting as a current carrying housing. The lead terminal portion is formed by a lead terminal and a stationary contact, and the lead terminal and the stationary contact are fixed with each other by welding. The lead terminal portion is mounted on the framework, the movable spring portion of the pushing, mechanism is accommodated within the framework, and the movable contact of the movable spring portion and the stationary contact of the lead terminal portion are located in matching position. In order to extinguish the arc, a permanent magnet is usually provided all around the framework. The arc is extinguished by means of the permanent magnet. Using the permanent magnet will cause the cost to be increased. Certainly, there is also a solution without any permanent magnets, in which solution the arc is extinguished by increasing the contact gap. In such solution, the contact gap has to be very large, which will lead to the disadvantages that the size of the product is increased and the acting time of the product is lengthened. In addition, welding the lead terminal and the stationary contact may also lead to the disadvantages of high cost and low efficiency.